Iterative Detection and Decoding Device for Selecting Soft Information According to at Least One Predetermined Constraint Rule, and Related Iterative Detection and Decoding Method

1. An iterative detection and decoding device, comprising: a signal detector, for generating a set of soft information (SI); a low-density parity check (LDPC) decoder which is an error-correction decoder, coupled to the signal detector, for iteratively decoding the set of SI and accordingly updating the set of SI to generate a set of updated SI; and an SI selector, coupled between the signal detector and the error-correction decoder, for selecting at least one SI from the set of updated SI when a binary summation of hard decisions of SI decoded from a same check node detector (CND) of the LDPC decoder is 0which is a predetermined constraint rule, wherein the signal detector further selectively generates a new set of SI according to a selection result generated from the SI selector.

2. The iterative detection and decoding device of claim 1 , wherein each SI included in the set of SI is a log likelihood ratio of a target bit.

3. The iterative detection and decoding device of claim 1 , wherein the predetermined constraint rule defines that hard decisions of SI fed back to a same variable node detector (VND) of the LDPC decoder should be the same.

4. An iterative detection and decoding method, comprising: generating a set of soft information (SI); iteratively decoding the set of SI by employing a low-density parity check (LDPC) decoding scheme and accordingly updating the set of SI to generate a set of updated SI; selecting at least one SI from the set of updated SI when a binary summation of hard decisions of SI decoded from a same check node of the LDPC decoding scheme is 0which is a predetermined constraint rule; and selectively generating a new set of SI according to a selection result of the step of selecting at least one SI from the set of updated SI.

5. The iterative detection and decoding method of claim 4 , wherein each SI included in the set of SI is a log likelihood ratio of a target bit.

6. The iterative detection and decoding method of claim 4 , wherein the predetermined constraint rule defines that hard decisions of SI fed back to a same variable node of the LDPC decoding scheme should be the same.

7. An iterative detection and decoding device, comprising: a signal detector, for generating a set of soft information (SI); a low-density parity check (LDPC) decoder which is an error-correction decoder, coupled to the signal detector, for iteratively decoding the set of SI and accordingly updating the set of SI to generate a set of updated SI; and an SI selector, coupled between the signal detector and the error-correction decoder, for selecting at least one SI from the set of updated SI when hard decisions of SI fed back to a same variable node detector (VND) of the LDPC decoder is the same and when a binary summation of hard decisions of SI decoded from a same check node detector (CND) of the LDPC decoder is 0, which is a predetermined constraint rule, wherein the signal detector further selectively generates a new set of SI according to a selection result generated from the SI selector.

8. An iterative detection and decoding method, comprising: generating a set of soft information (SI); iteratively decoding the set of SI by employing a low-density parity check (LDPC) decoding scheme and accordingly updating the set of SI to generate a set of updated SI; selecting at least one SI from the set of updated SI when hard decisions of SI fed back to a same variable node of the LDPC decoding scheme is the same and when a binary summation of hard decisions of SI decoded from a same check node detector (CND) of the LDPC decoder is 0; and selectively generating a new set of SI according to a selection result of the step of selecting at least one SI from the set of updated SI.